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This work demonstrates quasi-vertical β-Ga2O3 Schottky barrier diodes (SBDs) fabricated on c-plane sapphire substrates using an all-low-pressure chemical vapor deposition (LPCVD)-based, plasma-free process flow that integrates both epitaxial growth of a high-quality β-Ga2O3 heteroepitaxial film with in situ Ga-assisted β-Ga2O3 etching. A 6.3 μm thick (2̄01) oriented β-Ga2O3 epitaxial layer structure was grown on c-plane sapphire with 6° miscut, comprising a moderately Si-doped (2.1 × 1017 cm−3) 3.15 μm thick drift layer and a heavily doped (1 × 1019 cm−3) contact layer on an unintentionally doped buffer layer. Mesa isolation was achieved via Ga-assisted plasma-free LPCVD etching, producing ∼60° inclined mesa sidewalls with an etch depth of 3.6 μm. The fabricated SBDs exhibited excellent forward current–voltage characteristics, including a turn-on voltage of 1.22 V, an ideality factor of 1.29, and a Schottky barrier height of 0.83 eV. The minimum differential specific on-resistance was measured to be 8.6 mΩ cm2, and the devices demonstrated high current density capability (252 A/cm2 at 5 V). Capacitance–voltage analysis revealed a net carrier concentration of 2.1 × 1017 cm−3, uniformly distributed across the β-Ga2O3 drift layer. Temperature-dependent J–V–T measurements, conducted from 25 to 250 °C, revealed thermionic emission-dominated transport with strong thermal stability. The Schottky barrier height increased from 0.80 to 1.16 eV, and the ideality factor rose modestly from 1.31 to 1.42 over this temperature range. Reverse leakage current remained low, increasing from ∼5 × 10−6 A/cm2 at 25 °C to ∼1 × 10−4 A/cm2 at 250 °C, with the Ion/Ioff ratio decreasing from ∼1 × 107 to 5 × 105. The devices achieved breakdown voltages ranging from 73 to 100 V, corresponding to parallel-plate electric field strengths of 1.66–1.94 MV/cm. These results highlight the potential of LPCVD-grown and etched β-Ga2O3 devices for high-performance, thermally resilient power electronics applications.
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This content will become publicly available on June 1, 2027
Vertical β-Ga2O3 Schottky diodes with LPCVD-grown Sn-doped drift layer
High-quality Sn-doped (010) β-Ga2O3 homoepitaxial drift layers were grown by using the low-pressure chemical vapor deposition (LPCVD) method using solid elemental Sn as the n-type dopant source and integrated into vertical Ni/β-Ga2O3 Schottky barrier diodes to evaluate their device-level performance. β-Ga2O3 films with net carrier concentrations spanning from 2.0 × 1016 to 3.2 × 1017 cm−3 were achieved in thick epilayers exhibiting smooth surface morphology and high crystalline quality, as evidenced by surface rms roughness as low as 2.17 nm and an x-ray diffraction rocking-curve full width at half maximum as low as 38.9 arcsec. The fabricated diodes exhibited clear rectification and near-ideal thermionic-emission behavior, yielding ideality factors of 1.16–1.18 and Schottky barrier heights of 1.08–1.19 eV. The differential specific on-resistance (Ron,sp) decreased with increasing carrier concentration, with measured values ranging from 38.07 to 27.31 mΩ cm2. Temperature-dependent current–voltage measurements ranging from 25 to 250 °C showed stable thermionic-emission-dominated transport, with a gradual reduction in Schottky barrier height and an increase in on-resistance due to phonon-limited mobility. Capacitance–voltage (C–V) analysis confirmed uniform and controllable doping profiles and yielded barrier heights between 1.12 and 1.29 eV, depending on carrier concentration. Temperature-dependent C–V measurements revealed a systematic reduction in built-in potential and barrier height with increasing temperature. Reverse-bias measurements demonstrated a breakdown voltage of 225 V for a diode with a drift-layer carrier concentration of 2.0 × 1016 cm−3 in the absence of any field-management structures, with two-dimensional Silvaco technology computer-aided design (TCAD) electrostatic simulations revealing peak electric fields localized at the Schottky anode edge, indicating edge-field-limited breakdown. These results demonstrate LPCVD as a viable approach for the growth of Sn-doped β-Ga2O3 drift layers that support high-quality Schottky interfaces with stable operation over a wide temperature range, providing a foundation for continued development of β-Ga2O3 high power devices.
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- PAR ID:
- 10684488
- Publisher / Repository:
- AIP Publishing
- Date Published:
- Journal Name:
- APL Electronic Devices
- Volume:
- 2
- Issue:
- 2
- ISSN:
- 2995-8423
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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